ENGLEWOOD — The Denver Broncos have activated center J.D. Walton to their 53-man roster and placed guard John Moffitt on the reserve/left squad list.

Moffitt, a third-year pro from Wisconsin, didn't return from the team's bye week Monday. On Tuesday, he told 102.3 ESPN in Denver that he'd lost his love for the game and didn't want to keep playing just for a paycheck.

Moffitt also told the radio station he was thinking about his long-term health, saying, "scientists do know that hits to the head do deteriorate your brain," and that wasn't a risk he was willing to take any longer.

"I still love football," Moffitt said. "I just don't love doing it."

The Broncos have a five-day roster exemption on Moffitt, who was acquired from Seattle in August for defensive tackle Sealver Siliga.

Walton was the team's starting center until going on IR a month into the 2012 season with a broken ankle. He had a setback in his comeback this summer and began the season on reserve/PUP. He returned to practice three weeks ago.